Where to Buy Sodium Hydroxide

Measuring lye caustic soda for making soap

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Sodium hydroxide (NaOH), or lye, is a common ingredient in many science projects, particularly chemistry experiments, as well as in homemade soap and wine. It's also a caustic chemical, so it's not as easy to find in stores as it used to be. Some shops carry it as Red Devil lye with laundry supplies. It's also found, usually in an impure form, in solid drain cleaners. Craft stores carry lye for soapmaking. There is also food-grade sodium hydroxide, sold in some specialty cooking stores.

You can find sodium hydroxide online. You can purchase it at Amazon as sodium hydroxide or lye, pure lye drain opener, caustic soda, and pure or food-grade sodium hydroxide. Depending on your project, you may be able to substitute potassium hydroxide (KOH), which has similar chemical properties and is easier to find. However, these two chemicals aren't the same, so if you make the substitution, expect slightly different results.

How to Make Sodium Hydroxide

If you can't purchase sodium hydroxide, you can use a chemical reaction to make it. You will need:

  • Table salt (sodium chloride, nonionized)
  • 2 Carbon electrodes (from zinc-carbon batteries or graphite pencil leads)
  • Alligator clips
  • Water
  • Power supply (such as a 9-volt battery)
  1. In a glass container, stir salt into water until it dissolves. Do not use an aluminum container or aluminum utensils because sodium hydroxide will react with and damage them.
  2. Place the two carbon rods in the container (do not allow them to touch).
  3. Use alligator clips to connect each rod to a terminal of the battery. Let the reaction proceed for about seven hours. Place the setup in a well-ventilated space, as hydrogen and chlorine gas will be produced. The reaction produces a sodium hydroxide solution. You can use it as such or you can evaporate it off the water to concentrate the solution or obtain solid lye.

This is an electrolysis reaction, which proceeds according to the chemical equation:

2 NaCl(aq) + 2 H2O(l) → H2(g) + Cl2(g) + 2 NaOH(aq)

Another way to make lye is from ashes, as follows:

  1. Boil ashes from a hardwood fire in a small amount of distilled water for about half an hour. Getting a large amount of lye requires a lot of ashes. Hardwood ash (such as oak) is preferable to softwood ash (such as pine) because softer woods contain a lot of resin.
  2. Let the ashes sink to the bottom of the container.
  3. Skim the lye solution from the top. Evaporate the liquid to concentrate the solution. Note that lye from ashes is relatively impure but should be good enough for many science projects or to make soap.

To make a crude soap from homemade lye, simply combine lye with fat.

Sodium Hydroxide Projects

Once you have lye, use it in a variety of science projects. You can make a sodium hydroxide solution to use as a base, homemade soap, or water glass for homemade "magic rocks," or try the gold-and-silver "magic" pennies experiments.